/*
 * 版权：河南魔丸科技有限公司 版权所有
 * @author Zhaimm
 * 创建日期：2021/4/8 1:51 PM
 * 文件名：ZMBubbleTabIndicator
 */


import 'dart:math';

import 'package:flutter/material.dart';
import 'package:flutter/widgets.dart';

/// Used with [TabBar.indicator] to draw a horizontal line below the
/// selected tab.
///
/// The selected tab underline is inset from the tab's boundary by [insets].
/// The [borderSide] defines the line's color and weight.
///
/// The [TabBar.indicatorSize] property can be used to define the indicator's
/// bounds in terms of its (centered) widget with [TabBarIndicatorSize.label],
/// or the entire tab with [TabBarIndicatorSize.tab].
class ZMBubbleTabIndicator extends Decoration {
  /// Create an underline style selected tab indicator.
  ///
  /// The [borderSide] and [insets] arguments must not be null.
  const ZMBubbleTabIndicator({
    this.borderSide = const BorderSide(width: 2.0, color: Colors.white),
    this.insets = EdgeInsets.zero,
  }) : assert(borderSide != null),
        assert(insets != null);
  
  /// The color and weight of the horizontal line drawn below the selected tab.
  final BorderSide borderSide;
  
  /// Locates the selected tab's underline relative to the tab's boundary.
  ///
  /// The [TabBar.indicatorSize] property can be used to define the tab
  /// indicator's bounds in terms of its (centered) tab widget with
  /// [TabBarIndicatorSize.label], or the entire tab with
  /// [TabBarIndicatorSize.tab].
  final EdgeInsetsGeometry insets;
  
  @override
  Decoration lerpFrom(Decoration a, double t) {
    if (a is ZMBubbleTabIndicator) {
      return ZMBubbleTabIndicator(
        borderSide: BorderSide.lerp(a.borderSide, borderSide, t),
        insets: EdgeInsetsGeometry.lerp(a.insets, insets, t),
      );
    }
    return super.lerpFrom(a, t);
  }
  
  @override
  Decoration lerpTo(Decoration b, double t) {
    if (b is ZMBubbleTabIndicator) {
      return ZMBubbleTabIndicator(
        borderSide: BorderSide.lerp(borderSide, b.borderSide, t),
        insets: EdgeInsetsGeometry.lerp(insets, b.insets, t),
      );
    }
    return super.lerpTo(b, t);
  }
  
  @override
  _ZMRAPainter createBoxPainter([ VoidCallback onChanged ]) {
    return _ZMRAPainter(this, onChanged);
  }
  
  Rect _indicatorRectFor(Rect rect, TextDirection textDirection) {
    assert(rect != null);
    assert(textDirection != null);
    final Rect indicator = insets.resolve(textDirection).deflateRect(rect);
    return Rect.fromLTWH(
      indicator.left,
      indicator.bottom - borderSide.width,
      indicator.width,
      borderSide.width,
    );
  }
  
  @override
  Path getClipPath(Rect rect, TextDirection textDirection) {
    return Path()..addRect(_indicatorRectFor(rect, textDirection));
  }
}

class _ZMRAPainter extends BoxPainter {
  _ZMRAPainter(this.decoration, VoidCallback onChanged)
      : assert(decoration != null),
        super(onChanged);
  
  final ZMBubbleTabIndicator decoration;
  
  @override
  void paint(Canvas canvas, Offset offset, ImageConfiguration configuration) {
    assert(configuration != null);
    assert(configuration.size != null);

    final Rect rect = offset & configuration.size;
    final TextDirection textDirection = configuration.textDirection;
    final Rect indicator = decoration._indicatorRectFor(rect, textDirection);
    final Paint paint = decoration.borderSide.toPaint();
    
    final left = indicator.left;
    final width = indicator.size.width;
    final compare = left % width / width;
    final pW = 10.0;
    /// left的值计算会有微小误差，暂时这样判断能达到效果。(最优解重写TabBar)
    final startX = (compare < 0.995 && compare > 0.005) ? offset.dx - pW : offset.dx;
    final iW = (compare < 0.995 && compare > 0.005) ? rect.width + pW * 2 : rect.width;
    final iH = indicator.height;
    final pH = iH / 8;
    final radius = (iH - pH * 2) / 2 ;

    final Path path = Path();
    path.moveTo(startX + radius, pH);
    path.lineTo(startX + iW - radius, pH);
    path.arcTo(
        Rect.fromCircle(
            center: Offset(
                startX + iW - radius,
                radius + pH),
            radius: radius),
        -pi * 0.5,
        pi ,
        false);
    path.lineTo(startX + iW / 2 + pH, iH - pH);
    path.lineTo(startX + iW / 2, iH);
    path.lineTo(startX + iW / 2 - pH, iH - pH);
    path.lineTo(startX + radius, iH - pH);
    path.arcTo(
        Rect.fromCircle(
            center: Offset(
                startX + radius,
                radius + pH),
            radius: radius),
        pi * 0.5,
        pi ,
        false);
    path.close();
    canvas.drawPath(
        path,
        paint
          ..style = PaintingStyle.fill
          ..strokeWidth = iW
    );
    
    
    
  }
}